This invention relates to a fuel injection control system for controlling the flow of fuel from fuel injectors to an internal combustion engine and, more particularly, to such a system adapted to provide, to the fuel injectors, fuel-injection command pulses having a predetermined repetition rate and a pulse width calculated as a function of engine air flow.
Fuel injection control systems have been employed to control the flow of fuel from fuel injectors to an internal combustion engine by providing fuel-injection command pulses to the fuel injectors. The fuel-delivery requirement of the engine is calculated in the form of fuel-injection pulse-width and injection timing. The fuel-injection pulse-width is calculated from an algebraic relationship describing fuel-injection pulse-width as a function of engine air flow rate and engine speed. It is the common practice to meet the fuel-delivery requirements by providing, in synchronism with rotation of the engine crankshaft, fuel-injection command pulses, the pulse width of which corresponds to the flow of air supplied to the engine in each engine crankshaft rotation. However, this requires an engine-speed sensor for sensing the speed of rotation of the engine crankshaft, a reference pulse generator for generating pulses in synchronism with engine crankshaft rotation, and a data processing circuit therefor, leading to a relatively complex and unreliable fuel injection control system. Furthermore, a failure in the engine speed sensor, the reference pulse generator, or the data processing circuit will cause engine troubles.
The present invention provides an improved fuel injection control system which eliminates the above disadvantages found in conventional fuel injection control systems by providing fuel-injection command pulses having a predetermined repetition rate and a pulse width calculated as a function of engine air flow.